期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：15
页码：8793-8798
DOI：10.1073/pnas.1031592100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A two-locus gene conversion model with selection is developed. Under the joint action of selection, mutation, gene conversion, recombination, and random genetic drift, approximate formulas for the expectations of the moments of allele frequencies and the expected amounts of variation within and between two loci are obtained by a diffusion method assuming relatively strong selection. It is shown that the pattern of allelic variation is mainly determined by the balance between gene conversion and selection, because these two mechanisms act in opposite directions. As an application of the theoretical results, the human RHCE and RHD genes are considered. The very high level of amino acid divergence between the two genes is observed only in a short region around exon 7. It is known that exon 7 encodes amino acids that characterize the difference between the RHCE and RHD antigens. The observed pattern of DNA variation in this region is consistent with the selection model developed in this article, suggesting that strong selection might be working to maintain the RHCE/RHD antigen variation in the two-locus system. The selection intensity is estimated on the basis of the theoretical result.
